1. Field of the Invention
The invention comprises a process and a device for the catalytic cracking of hydrocarbon molecules at temperatures of 300-400° C. using alkali-doped aluminum silicates as catalyst, where the energy input is provided primarily by a combination of pumps and agitators, which are connected to a separation tank for the separation of mineral contaminants.
2. Description of the Related Art
Catalytic depolymerization using a special catalyst consisting of sodium-doped aluminum silicate is known from DE 100 49 377. With the use of this catalyst, the hydrocarbon-containing residue is cracked into diesel oil and gasoline. The heat required to produce the energy for cracking, the energy required to evaporate the cracked hydrocarbons in the form of diesel oil and gasoline, and the energy for the initial heating phase and also the heat required to make up for losses are supplied in this case by heating through the wall.
The disadvantage of this process is that, because of the wall, the heating temperature must be higher than the reaction temperature. As a result, a certain amount of reaction coke is always formed. When the temperature of the wall increases relative to the temperature of the reaction mixture, that is, when a certain production output is to be obtained, the amount of coke will also increase.
This reaction coke now reacts with the sodium-doped aluminum silicate to form a nonreactive residue, which contaminates the system and brings the reaction to a standstill. This reaction mixture of catalyst and reaction coke interacts with the wall of the device, forming a hard residue, and a great deal of effort is required to clean it off during the scheduled maintenance intervals.
An economical process is therefore impossible to obtain by heating the wall intensively, that is, by attempting to supply heat actively by conducting it through the wall. The lower thermal conductivity of the reaction oil in the circuit results in a greater temperature difference between the heating located externally on the wall and the reaction in the oil, which the cracking energy (depolymerization), the evaporation energy, and the heating energy require.
If there is only waste oil and tars in the oil circuit, approximately 0.4 kWh of energy is required per kg of evaporated diesel for cracking, for evaporation, and for raising the temperature from the inlet temperature of 250° C. to the reaction temperature of 390° C. When plastics are added to the feedstock, the energy requirement is almost twice as high, because these materials are loaded cold and extra energy is required to melt them.